deleted trailing ENTERs
documented \[\]
<Oper Name="\[\]" and <Func Name="SI_\["
documented SI_std
mention the design mistake in Plural
deleted trailing ENTER
documented SI_syz
fixed docu headers
new paragraphs
documented rest of matrix functions without examples
added missing <P/>
SI_ring: improve ordering support

Fixes #11
Fix some typos
Get rid of SI_DEBUG_MODE
Replace bad assert in SI_CallProc by TODO comment.

Fixes #47
gapwrap: report singular objects with unknown / unsupported type
Add / move some tests
Slightly improve SI_CallProc return value handling

This fixes some versions of issue #48, but not all of it. In particular
the example given in the issue still is broken :-/.
Cleanup code formatting (mostly whitespace)
Add some more tests cases (including one which creates a map object)